Underwater acoustic decoy



June 14, 1955 4 Sheets-Sheet 1 Filed June 14, 194:5

grr/umm on ou o w o O Duo o June14, 1955 D. G. REED V UNDERWATER ACOUSTIC DECOY 4 Sheets-Sheet 2 Filed June 1-1a7 1945 FEG. 4

FIG. 5

Syvum/1m l DONALD G. REED June 14, 1955 Q G, REED 2,710,458

UNDERWATER ACOUSTIC DECOY Filed June 14, 1945 4 Sheets-Sheet 3 DONALD G. REED @WLM June 14, 1955 D G, REED 2,710,458

UNDERWATER Acous'rrc nEcoY F11ed June 14, 1945 4 sheets-sheet 4 d20/'gif INVENTOR ooNALne. REED BY I s i ATTORNEYS United States Patent UNDERWATER ACOUSTIC DECOY Donald G. Reed, San Diego, Calif., assignor to the United States of America as represented by the Secretary of the Navy Y Application June 14, 1945, Serial No. 599,501

9 Claims. (Cl. 35-25) This invention relates to submarine decoys and more particularly to a device which, when placed in the water, emits sounds similar to those produced by a submarine.

The invention described herein is a mechanism which finds use in training sound gear operators in locating submerged submarines and also in assisting a submarine in evading detection,Y damage, or destruction during encounters with enemy vessels equipped with sound gear.

The use of the invention for training purposes is desirable in that it provides a source of underwater sound which, when observed by sound gear, produces the noises characteristic of a submarine. Thus, since it is a small, compact unit and may be considered expendible, it serves toV train sound operators without the necessity for assigning an actual submarine to training exercises. It may or may not be'made self-propelled and thus may simulate a submarine either lying to or underway.

Its use as an evasive mechanism is equally important, in which case, a unit, generally of the self-propelled type, is ejected from a submarine. The noises which the unit produces, resembling those made by a submarine, are thus heard and may be confused with the actual submarine. While these noises are being produced, the ejecting submarine may thus be enabled to slip away undetected or unharmed while the enemy concentrates his etorts toward the destruction of the decoy.

As has been stated, the preferred embodiment of the invention is one which is small and compact in order to eliminate difficult handling and storage problemsand which, whenused as an aid to evasion, can' be ejected from existingmechanisms on submarines, i. e., torpedo tubes, or are guns, while the boat is submerged and/or underway. Obviously, too, the preferred form comprises means for propelling the unit to increase the degree of simulation. Several forms will be described herein, but a small self-'propelled unit will be described and illustrated in detail.

y In the drawings:

Fig.` l is an external viewA of a self-propelled form of the invention.l

Fig. 2 is a View of the device shown in Fig. 1, partially in section, showing the relation of elements and their manner of operation.

Fig. 3 is a sectional view of the tail section of the device shown in Fig. l taken in a vertical plane and showing the .control mechanism.

Fig. 4 is a sectional'view of the portion of the unit shown in Fig. 3, taken in a horizontal plane.

Fig. 5 is any elevation of the motor and noise-making mechanism.

Fig. 6 is a partial section of the noise-making mech-. chanism taken along the lines 6 6 of Fig. 5.

`Fig. 7 is a partial section of the noise-making mechanism taken along the lines 7-7 of Fig. 6, but with the eccentricly hubbed gear and its shaft removed.

Fig.' 8 is a sectional view of the noise-making mech anism along the lines 8- 8 ofV Fig. 5

Fig. 9 is a view of another form of the invention pro- 2,710,458 Patented June 14, 1955 ,s ICC vided with a buoyancy control by means of which it is supported in the water.

Although the invention may be embodied in a variety of forms, one of the preferred forms is a small, selfpropelled unit, approximately 33t/2" long and 3 in diameter. Such a device is shown in Figs. l to 8 and is provided with a spun metal nose 1 of the shape shown in Figs. l and 2, a tubular motor housing 2, a tubular battery housing 3, a buoyancy chamber 4 and a tail section 5, on which are mounted the rudder and diving vanes, all of v which t together to form the body of the unit.

As shown in Fig. 2, a motor 6, mounted within the motor housing 2, is connected to drive a propeller shaft 7 which extends through a water-tight bushing 8 in the nose section 1. The tractor propeller 9 is fixed to the outer end of shaft 7 by means of a set-screw 10 and serves to propel the device through the water. The rearward end of the nose section 1 is provided with an inwardly extending flange 11, the outer circumference of which is offset as at 12 to receive the adjoining end of the motor housing 2. The joint is made watertight by a rubber washer 13 mounted in a recess in the flange and a series of small pins 14 is used to tix the units against slippage.

The rearward end of the motor housing is closed by a watertight bulkhead 15 provided with a flange, a recess, and a gasket, similar to those just described on the nose section, and receives the motor housing 2 as shown in Fig. 2. The bulkhead 15 is also provided with an oiset to receive the battery housing 3 and the two are held together by pins, similar to pins 14.

The rearward end of the battery housing 3 and the forward end of the buoyancy chamber 4 are held together by means of a bulkhead 16 (with its associated flange, pins and gaskets), which is similar to bulkhead 15. The rear ward end of the buoyancy chamber is closed by a similar, but smaller, bulkhead 17 which is fixed and made watertight by the same construction used on bulkheads 14, 15 and 16. The tail section 5 is similarly pinned to the bulkheads ange to complete the body assembly.

It is noted that the battery housing 3 and the tail section 5 are made free-ilooding by means of holes, as at 18. Thus, the joints between these two sections and their adjoining bulkheads are not required to be watertight.

The tail section, as shown in Figs. 3 and 4, supports a vertical rudder 19 which may be tixedly secured to it by rivets, bolts or by soldering or welding. At the bottom of the rearward edge of the rudder, a small horizontal cut is made in the surface which forms a tab, as at 20. By slightly bending this tab to the right or left, the course of the unit may be made straight or curved, as desired. The rudder also supports a short, cylindrical shroud ring 21 which helps to stabilize the unit while it is in motion.

The device is also provided with two self-adjusting diving planes 22, 23 one of which is located on either side of the body and connected together for simultaneous movement by a shaft 24 secured to them by an convenient means. This shaft extends through the tail section which is provided with a pair of oppositely positioned elongated holes in its rearward portion, as at 25 (as shown in Fig. 1). The shaft 24 is journaled in gimbal 26, said gimbal being mounted for limited rotation about the central axis of the device. This is accomplished by providing it with two short shafts 27, 28, one located at either end, and which rest in bearings 29, 30. The forward bearing 29 may be formed integrally with bulkhead 17,

while the after bearing 30 is shown to be mounted by means of a bolt 31 through the end of the tail section. A collar 32 is secured to the central portion of shaft 24 by means of releasable set-screws 33 and is provided with an upstanding ear 34. A small pressure-actuated Sylphon bellows 35 is positioned within the tailv section and an arm 36, extending from one of its ends is pivotally secured` to the ear 34 on collar 32` by means of a pin 37. The opposite end of the bellows 35 is supported by means of a yoke 3S to which it is secured by an inwardly extending bolt 39 (which also acts to prevent too great contraction of the bellows when it is under great pressures). The yoke, in turn, is pivoted on a shaft 40 which is supported by a pair of swinging arms 41. These arms support a relatively heavy weight 42. at their lower ends and are pivoted about a pin 43 secured in a support 44, which support is iixedly secured to gimbal 2'6.

The operation of the diving control mechanism just mentioned' is such as to enable running of the device at a pre-determined depth in a manner that any change in depth is immediately ecctive to cause the unit to return to said depth. The only original adjustment required is the angular position of diving vanes 22, 23 and shaft 24 with respect to collar 32 and which may be made as desired by means of set-screws 33. This A setting is, ofcourse, determined by Calibrating the effect of varying pressures on the particular bellows used.

To illustrate the operation, assume the unit is ejected at the depth at which it is set to run and assume that it is running level. if, for some reason, the nose heads downward to a` greater depth, the weight 42 rotates forward about pin 43 and causes yoke 38, bellows 35 and arm 36 to move forward. The motion of arm 36 causes rotation of the diving vanes 22, 23 through ear 34, collar 32 and shaft 24. The new position of the diving vanes is such as to cause the unit to rise. Conversely, if the unit assumed a climbing position with its nose higher than the tail, the rotation and shift of weight 42, in the same manner, causes the vanes to be rotatedy in the opposite direction to effect a dive.

All of the motions outlined above are unaffected by a limited rolling or tipping of the unit about its longitudinal axis, as the whole control mechanism is designed to rotate on bearings 29 and 30, being limited in rotation only by the length of the elongation of the holes 25, and thus maintains itself, because of the effect of Weight 42, in the same position relative to the horizontal.

The depth which the unit naturally seeks is determined by the size and strengthv of bellows 35 and the original angular relationship of the diving vanes 22, 23 with respect to collar 32, as stated above. Since this latter relationship may be varied by means of set-screws 33, as desired, any running depth may be pre-set into the device. When the unit reaches the proper level, the length ofthe bellows, as determined by the pressure, will be such that the vanes are set to cause neither diving or rising of the unit. If, however, the unit is ejected at too great a depth, the contraction. of the bellows causes the diving vanes to assume a position which causes the unit to rise; and conversely, a lesser pressure than is existent at the pre-determined depth causes expansion of the bellows, rotation of the diving planes in the opposite direction, by reason of which a dive is effected.

There are two general methods by which the simulation of noises might be accomplished,v electronic and mechanical, the former of which would comprise apply ing electrical signals to one or another of various types of transducers. The method illustrated herein, however, is mechanical, and the mechanism is shown. in detail in Figs. 5 to 8. Power is supplied by the small D. C. motor 6 (which may be a 6 volt Buss unit, K. & D., 90L) which, as has been described, drives propeller 9 by means of shaft 7. The motor and noise-making mechanism is mounted within the motor housing 2 on three supports 45, 46, 47, as shown in Figs. 2r and 5. A support 48, formed as a part of the motor, acts as a bearing for the motor armature and the shaft 7, but is directly connected by means of bolts 49 and spacers 5 0 to support 46.

A worm 51 is keyed to shaft 7 and is positioned between the supports 46, 47, to engage a gear 52'. This gear is provided with a slightly eccentric hub 53, as shown in Fig. 6, and is fixed to a short shaft 54. The shaft is supported at its ends by a pair of blocks 55 which are fixed to supports 46, 47 by any convenient means. Adjacent the gear 52 is a small sliding block 56 provided. with a counterbore to receive the eccentric hub 53 of said gear, as can be seen in Fig. 6.v The lower end of the. sliding;l block: 5.6i is providedY with. an openingextending parallel to shaftv 7T. A shaft 57: is positioned for rotation within this opening in block 56 andi extends through aligned. openings in supports. 46, 47. A pair of gears 58, 59 are keyed to the opposite ends of shaft 7, outwardly of? the supports, oneof which, gear 58, is positioned to engage and be driven by gear 60 which is keyed to shaft 7. The other, gear 59, is positioned Vto drive gear 61 which is supported substantially concentrically with but free of shaft 7' by means of an adjustable eccentric bushing` 62. mounted in the upper portion of support 47', the eccentric bushing 62 serving to adjust the normal clearance between gears 59 and' 65 sorv as to compensate the noisemakerl for manufacturing discrepancies. The upper portion of support 47 is made somewhat ilexible with respect to the remainder bymeans of a saw cut,V as at 63, as is seen in Fig. 8, but it is held against excessive relative motion by means of a bolt 64 and spacer 65, joining it to support 46.

In operation motor .6. turns shaft 7 and worm 51 rotates gear 52. The eccentric hub 53 of this gear, as it rotates, causes block 56 to slide up and down against adjacent block 55. YThis transmits the same motion through shaft 57 to gearsA 58, 59 and these gears are thus caused to engage gears 60, 61 to greater andlesser degrees as rotation takes place. At the same time, the shaft causes rotation of gear ,60,r which drives gear 58 and, in turn, gear 59 through shaft 5'4. Gear 59 causes corresponding rotation of gear 6.1.

Both the upper and lower ends of supports 45, 46, 47 are formed to be supported snugly against the. inner walls of motor housing 2, as shown in Fig. 2. This insures thev transfer of any vibrations (i. e., sonic and/or supersonic energy) to the walls of the unit and thus into the surrounding water. As is obvious, this energy has several sources such as rotation of the motor 6' land shaft T, engagement of the various gears, the variation in such engagement, and the movement imparted to the upper flexible portion of support 47;,and its spectra is thus determinedV by the particular construction used and the speed at which the motor 6 is rotated.

In practice it lis found that, for the arrangement shown, the energy produced is primarily in the sonic range, but with appreciable components in the supersonic range, when motor 6 is run at approximately 5000 R. l. M. The engagement of the gears simulates to a high degree the gear whine characteristic of actual submarines and the variation of such engagement also simulates the thrashing noises made by a submarines propellers. By arranging the speed of motor 6, this variation may be made to occur at a frequency characteristic of a submerged submarine underway.

ther and different mechanisms could be used to produce these simulating sounds, all of which will be familiar to those skilled invtheart. The one illustrated, however, has been found to beexceedingly useful. and produces a high degree of simulation.

The power supply 66 is mounted in the' free-llooding battery housing 3 between bulkheads 15, 16. In the form shown in Fig. 2, this battery is a sea-activated type (such as a Burgess 5CC-133). It comprises spirally woundvthin sheets of dissimilar metals, which act as electrodes. These are insulated from one another and becomev active only when .the compartment is hooded, with the seawater acting as the` electrolyte. The unit4 shown supplies some 133 ampere; minutes at 7:4 volts, which is suicient to operate motor 6 for approximately 15 minutes. Other conventional types of batteries may also be used, such as four cells of Willard NT6 (Navy type CWB 19046) units, with approximately the same capacity. Obviously, if this latter type unit is used, the holes, as at 18, in the battery housing 3, are omitted.

Leads 67, 68 are taken off the battery 66 and brought through bulkhead by means of watertight terminals 69 and connected to the motor terminals. Power is thus supplied to the motor as soon as the unit is submerged,4 if a sea-activated battery is used, or, if a conventional unit is utilized, a switch, manually or automatically operated after a predetermined delay time, may be included in the circuit to start the motor.

An additional feature of the present model is a balancing mechanism to prevent rotation about the axis of the body and to prevent the'reaction against the rotation ofV the motor and noise mechanism from causing angular movementv about said axis. This mechanism consists simply of a relatively heavy weight 70 shaped to conform tothe inner side of bulkhead 16 and which may be slid around the inner circumference. It supports a threaded bolt 71 fixed in position by a lock-nut 72 and is engaged at its outer end by an adjustable pointed nut 73 which, in turn, engages the opposite side of the bulkhead. By loosening thenut 73, the weight 70 canbe slid around the bulkhead to a new position where it may be fixed by again tightening the pointed nut.

The type of decoy shown in Fig. 9 is similar to that shown in Figs. 1-8 and described above, except that it is not self-propelled, but is provided with a buoyancy control mechanism, by means of which it may be suspended at a predetermined depth for a predetermined time regardless of whether it is thrown into the water at the surface or ejected by a submarine.

In this embodiment, the noise-making mechanism may be the same as that illustrated in connection with the self-propelled model described above and it may be contained in the same general type of metal tube or body. However, in this case, the propeller assembly is not included and the motor is arranged to drive only the noise- 'making mechanism. The tail control assembly is also not necessary, nor are the curved end surfaces. As shown in Fig. 9, the main body section 80 is the same as that used in the self-propelled model but is closed at the lower end by means of a watertight bulkhead 81. The battery may also be housed identically with that described in conjunction with the self-propelled device. However, at the end of the unit most remote from its center of gravity, a buoyancy control mechanism 82 is provided and attached to the body by means of a bracket 83.

This mechanism may be of the type described in an application for Letters Patent, Serial No. 533,895, filed May 3, 1944, by Raymond D. Atchley, or of any other convenient type.

If the construction shown in Fig. 9 is used, the device may be utilized and ejected much in the same manner as is the self-propelled type described. If so, it will support itself at a predetermined level in the water until the gasproducing chemical provided in the buoyancy control 82 is completely exhausted, after which the entire unit will sink to the bottom. This construction is obviously simpler than the self-propelled decoy, and although the simulated submarine sounds will be clearly audible, they will appear to emit from a stationary source.

From the description of the invention set forth above` the manner of its use is obvious. Regardless of whether the unit is self-propelled or not, when used in training sound gear operators, it is dropped into the water by the training ship or another vessel and practice attack runs are made upon it as though it were an actual submarine. If used as a training aid, it may be made very slightly positively buoyant so as to surface at the end of the run, if self-propelled. If the stationary type is utilized in training, it may be provided with a oat or any other conventional mechanism for insuring recovery' at the end of the exercise.

When utilized as a decoy against enemy vessels, the unit is considered expendible and is made slightly negatively buoyant so that after it has ceased operation, it sinks to the bottom. In the self-propelled type, this will occur when the battery ceases to supply energy to drive the motor; and in the stationary unit, when the chemical in the buoyancy control mechanism is exhausted.

Upon ejection from a submarine, the self-propelled device will normally be set to run in a direction generally away from the evasion course of the submarine in order to give the best opportunity for escape and in the hope that the submarine can travel a material distance while the enemy ships are engaged with the decoy.

Having described my invention, I claim:

Vl. A Vdevice for simulating the Vsounds produced byV a' submarine, comprising: a housing adapted to travel through a liquid and having therein a source of energy, a motor operable by said source of energy, a noise-maker adapted to transform power from said motor into sound whereby sounds of varying intensity are broadcast, said noise-maker having a rotatable driving shaft, a worm' gear mounted on said shaft, a worm wheel associated with said worm gear, said worm wheel having a hub, said hub having an eccentric outer surface, a sliding block associated with said worm wheel whereby rotation of said worm wheel through said hub causes reciprocating motion of said block, a second shaft journaled in said block, gears mounted on the ends of said second shaft, gears mounted on said rotatable driving shaft, one of said gears on said driving shaft iixedly mounted thereon and adapted to drive one of the gears on said second shaft, the other gear on said second shaft adapted to drive the other gear on said driving shaft.

2. A device for simulating the sounds produced by a submarine, comprising: a housing; a mechanical noise making mechanism in said housing, said mechanism comprising a train of gears, one or more of said gears adapted to vary in mesh with another gear or gears whereby the rotation of said gears produce sounds of varying intensity; propelling means for driving said device through a liquid; means for driving said train of gears and said propelling means; a fixed rudder connected to said housing; diving planes for the control of said device in elevation; pres` sure responsive means connected to said diving planes for automatic control of said device in elevation.

3. A device for simulating the sounds produced by a submarine, comprising; a housing; a mechanical noise making mechanism in said housing, said mechanism cornprising a train of gears having driving and driven members, some of said members constructed and arranged to vary in position with respect to their driving or driven mate during rotation; propelling means for driving said device through a liquid; means for driving said train of gears and said propelling means; a fixed rudder connected to said housing; diving planes for the control of said device in elevation; pressure responsive means connected to said diving planes for automatic control of said device in elevation.

4. A device for simulating the sounds produced by a submarine, comprising; a housing; a motor in said housing; a source of energy for said motor; a noise making apparatus operable by said motor, said apparatus comprising a train of gears, one or more of said gears adapted to vary in mesh with another gear or gears during rotation whereby sounds of varying intensity are broadcast during the rotation of said gears.

5. A device for simulating the sounds produced by a submarine, comprising: a housing; a motor in said housing; a source of energy for said motor; a noise making mechanism operable by said motor, said mechanism comprising a train of gears, one or more of said gears adapted to vary in mesh with another gear or gears during their rotation whereby sounds of varying intensity are. created; and; bouyancy means for suspending said-.device in a liquid at a predetermined depth.

6,. A. det/,ice tor simulating the sounds; produced by a submarine, comprising;` a housing; a source of energy therein; a, motori` operable, by said souroe of energy; a noise making mechanism adapted to transform power fromV saidl motor,y into sound, said mechanism comprising supporting members for al pair of rotatable shafts, each Qi Said Shafts having a plurality of gears mounted; there: 011,. means for varying the meshing engagement of the gears onl the one shaftY with the gearsV on the. other shaft, one of said supporting members having a. flexible portionA whereby said gears are permitted to rotate, regardless of, the mover-nent of. their shafts toward each. other.

7. An underwater decoy for: simulating a submarine Comprising an elongated. cylindrioal casing,V motor.- inea-ns, propeller means driven by the. rnotor means, and gear reducing; noise generator means; driven by the. motor Illia1-1sv operative to simulatey submarine propeller noise of; lower'v frequency than said decoy prtipeller.

8. A device for simulatingthe Sounds produced by a submarine comprising: a body section; means. for prof pelling said device through a liquid; a girnba-lmounted foi; limited rotation. about an axis parallel to the longitudinal axis of said body section; a control surface mounted for rotation in said gimbal about; an axis perpendicular to said longitudinal axis and forseparate rotation With said gimbal; means controlled by a pendulum, for maintaining the position of said girnbal regardless ofy limited rotation of said body section about Said longitudinal axis; and means controlled by said pendulum for causing simultaneous rotation of said surface about said axis perpendicular to said longitudinal axis in an angular amount greater than the rotation 0f Said body section about a horizontal axis perpendicular to said longitudinal axis.

9,. A device for simulating the sounds produced by a lia ,mounted fon rotation; in said'l girnbalabout an axisl perpendicular to. said longitudinal, axis and; for separate ro.- tation with said gimba1; ,rneans controlled by a. pendulum, for maintaining the position of said surface regardless of limited rotation. of said` body section about said longitudinal axis; means controlled by said. pendulum for causing; simultaneous rotation of said surface about said aXVS. pilllerlflilllal: t0, Said; longitudinal axis in; an angular amount greater than tbe: rotation Qi said body section about a horizontal axis perppnditilar to said longitudinal, axis; and nressure.=as tuated means toron ating; Said cnn-trol snr-tage; to etfeotmotion of; said devis, in. a sub.- stantiallyl horizontal plane,

Referencesctaa the rire or uns. patent UNITED STATES PATENTS 1,033,810 Leavitt July 30, 1912,' 1,145,355; Dieter July 6, 19,175 1,296,332 Shonnard Mar. 4, 1 919 1,308,003 Elia June 24, 1919 1,351,540; Roos Aug. 31, 192,0 1,625,245 Dorsey Apr. 1 9, 1927 2,009,451.' Kunze July 30, 1935 2,138,036 Kunze Nov. 2,9, 1938 2,352,862 Rabuse July 4, 1944 2,353,360 Ronning July 1l, 1944: 2,397,107 Hammond' Mar. 26, 1946 2,406,111 Sheffield Aug. 20, 1946 OTHER REFERENCES Websters Unabridged Dictionary, 1939, page 2689 under transducen 

